The present invention relates to a language manager for a database management system (DBMS).
The advent of powerful, yet economical computers has made these machines an integral part of many organizations. An important class of application for these computers includes a database, which is a body of information that is logically organized so that the information can be stored, searched and retrieved by a "database engine"--a collection of software methods for manipulating data in the database. The database allows users to perform operations such as locating, adding, deleting and updating records stored in the computer without a detailed knowledge of how the information making up the records actually is stored in the computer.
One powerful type of DBMS is known as a relational DBMS where stored information appears to the user as a set of tables, each of which is termed a "relation". In each relation, the information is arranged in rows and columns, with columns of data being related to each other by one or more predetermined functions. Further, each column has an attribute and each attribute has a domain which includes data values in that column. The structure of a relational database can be modified by selectively redefining relationships between the tables.
A database engine may perform complex searches on a relational database quickly and easily by using any of various database query protocols such as the method expressed by the Structured Query Language (SQL) or by other mechanisms. The relationships between the tables enable results of a search to be cross-referenced automatically with corresponding information in other tables in the database. A variety of operations made be performed on the tables in the database, including join, project and select operations. These operations may be made to standard as well as to user-defined data types.
To access a particular item of information in the relational DBMS, a query compiler converts a user request typically expressed in SQL into a set of operations to be performed on one or more input relations to yield a solution in response to the user request. Moreover, the user request may, under certain predetermined conditions, cause one or more user-defined routines (UDRs) to be executed. These UDRs may be implemented either as internal programs or external programs.
An internal program is a program that executes within the execution environment managed by the DBMS. The internal program typically is written in an interpretated language that is supported only within the DBMS environment. In contrast, an external program is capable of running in an environment managed by an operating system. External programs typically are expressed in a high level language which may be proprietary or may be a standard language such as Ada, Basic, C, C++, Cobol, Java, Pascal, or a fourth generation programming language, among others.
Although most relational database management systems support predefined procedures implemented as internal programs, not all systems support external programs. Moreover, in systems that support external programs, the language supported may be interpreted, as opposed to compiled, leading to suboptimal processing performance. Other systems hard-code their support of specific languages. These systems are inflexible in that a modification of an existing language or an addition of a new language is tedious.